Cladding is a welding procedure that puts weld metal on the surface of the work, as opposed to joining two pieces of material. Generally this is used for corrosion resistance or wear resistance and frequently a different material is used for the clad than for the base metal. In hot wire welding, the power supply controls the heat of the filler wire prior to its introduction into the weld puddle. Arc energy that would usually go into melting the wire provides more penetration, while heating of the wire almost to the melting point by a separate power supply increases deposition beyond that possible with standard cold wire TIG. In cladding applications where the part is rotated, the hot wire solution can result in weld deposition that approaches MIG speed, but with TIG quality.
Photographs of cladding: